Paediatrics: Acute respiratory diseases

Acute respiratory diseases

All of the diseases presented below have signs of respiratory distress. Cerebral hypoxia, congenital heart disease, and metabolic aci-dosis can induce respiratory distress (suspect if CXR is normal).

Transient tachypnoea of the newborn (TTN)

•   Caused by delayed clearance/absorption of lung fluid after birth.

•   Presents within 4hr after birth. Common after elective CS. CXR: shows streaky perihilar changes and fluid in lung horizontal fissures.

•   Treatment: supplemental O₂. Consider nasal CPAP and antibiotics.

•   Spontaneously resolves within 24hr.

Congenital pneumonia

•   Caused by aspiration of infected amniotic fluid.

•   Associated with prolonged rupture of membranes (PROM), chorioamnionitis, foetal hypoxia.

•   Usually group B streptococci, Escherichia coli, other Gram –ve bacteria, listeria, chlamydia.

•   Presents in first 24hr. CXR: patchy shadowing and consolidation.

•   Respiratory support: antibiotics (benzylpenicillin, or ampicillin if listeria, and gentamicin) after septic screen; chest physiotherapy.

•   Prognosis: depends on severity and associated sepsis or persistent pulmonary hypertension of newborn (PPHN).

Meconium aspiration syndrome (MAS) (1–5/1000 live births)

•   5% of term infants with meconium-stained liquor develop MAS.

•   Hypoxia results in gasping and meconium passage in utero, a combination that leads to aspiration. Meconium aspiration inhibits surfactant, obstructs the respiratory tract, and induces pneumonitis.

•   Presents with respiratory distress soon after birth. Associated with pulmonary air leaks and PPHN. CXR: generalized lung over inflation with patchy collapse/consolidation +/– air leaks.

•   Prevention: if liquor is meconium-stained, delivery should be expedited to prevent further hypoxia and gasping. If baby is apnoeic at birth, visualize the larynx and suck out any meconium from larynx/trachea. Tracheal suction is not recommended for vigorous infants.

•   Treatment: supplemental O₂; intermittent positive pressure ventilation (IPPV) or high frequency oscillatory ventilation (HFOV) if ventilation required; surfactant; antibiotics (since listeria can cause antenatal meconium passage); treat any PPHN; consider ECMO if severe.

•   Prognosis: mortality <5%. Survivors do well, but there is ‘rise’risk of asthma and, if extracorporeal membrane oxygenation (ECMO) is needed, neurological sequelae.

Pulmonary air leaks

Commonly secondary to other respiratory disease (e.g. RDS, MAS) or to assisted ventilation.

Pneumothorax

Spontaneous pneumothorax occurs in 72% term infants. Incidence is increased in prematurity and respiratory disease.

• Features: majority are small, asymptomatic, and resolve spontaneously. If large, present with respiratory distress. Tension pneumothorax is life-threatening (signs: respiratory distress, cyanosis, mediastinal shift away from affected side, ‘fall’ chest movement and air entry on affected side, transillumination lights up affected side).

• CXR: shows ipsilateral translucency, lack of peripheral lung markings, collapsed lung (see Fig. 6.4).

• Treatment: none if asymptomatic. Give O₂ as required. If symptoms are severe or worsening, insert chest drain. In emergency, perform needle aspiration before chest drain.

• Prognosis: excellent in term infants. Mortality is doubled in infants with RDS. Also ‘rise’risk of periventricular haemorrhage in preterms.

Pulmonary interstitial emphysema (PIE)

Air leak into lung parenchyma results in small airway and alveolar col-lapse. Follows high IPPV, particularly in preterm infants with severe RDS or MAS.

• Signs: respiratory distress; chest hyperexpansion; poor air entry; coarse inspiratory crackles.

• CXR: hyperinflation; ‘honeycomb’ pattern of cystic lucencies/bullae, generalized or local (see Fig. 6.5).

• Treatment: high FiO₂, low PIP, low PEEP, fast rate IPPV; HFOV may be

•   superior. Unilateral PIE: nurse infant with affected side down. In refractory cases consider selective intubation to ventilate the healthier lung.

• Prognosis: mortality 25–50%. There is an increased risk of bronchopulmonary dysplasia.

Pneumomediastinum

Often preceded by asymptomatic pneumothorax/PIE.

• CXR: translucency around the heart extending superiorly; thymus lifted and splayed from below (‘sail’ sign).

• Treatment: usually no treatment is required.

Pneumopericardium 

Usually occurs with other air leaks associated with IPPV and can lead to cardiac tamponade (with quiet heart sounds, hypo-tension, bradycardia, cyanosis).

• CXR: translucency around the borders of a small heart.

• Treatment: urgent needle drainage inserted under the xiphisternum.

• Prognosis: high mortality if symptomatic.

Pneumoperitoneum 

Air can occasionally track into the peritoneum from a pulmonary air leak. AXR confirms the diagnosis. Severe abdominal disten-tion could impair ventilation. Drain if symptomatic.

Massive pulmonary haemorrhage (1/1000 live births)

Usually due to haemorrhagic pulmonary oedema in VLBW infants. Small bleeds are associated with tracheal trauma from ETT or suction. It is associated with: PDA, heart failure, PIE, hydrops foetalis, perinatal hypoxia, sepsis, coagulopathy, fluid overload, surfactant therapy

Signs

•   Rapid systemic collapse.

•   Profuse bloodstained fluid welling up from upper airway.

•   Respiratory crackles on auscultation.

•   CXR. Virtual ‘white out’. Consider echocardiography to detect PDA.

Treatment

•   rise O₂ and ventilatory pressures.

•   Frequent endotracheal suction.

•   Correct hypovolaemia and coagulopathy.

•   Consider blood transfusion.

•   Consider surfactant.

•   Treat known associations.

Milk aspiration

Term infants can accidentally aspirate a feed. The usual causes are:

•   Swallowing incoordination, e.g. preterm, neurological disease.

•   Upper airway or oesophageal disorders, e.g. tracheo-oesophageal fistula, gastro-oesophageal reflux.

Presentation

Sudden choking or respiratory distress during or after a feed, often with excessive milk in the mouth, or aspiration pneumonia.

CXR: normal or patchy collapse/consolidation in the upper lobes.

Treatment 

If well, observe only. If unwell, respiratory support and broad spectrum antibiotics are needed. Investigate cause and use gastric or naso-jejunal tube feeding. Period of IV fluids or feeding may be necessary.

Apnoea

Apnoea can result from any severe illness.

Management

•   Support respiration.

•   Investigate and correct primary cause.

Apnoea of prematurity

•   Common below 34wks gestation (incidence ‘rise’as gestation d).

•   Between episodes the infant is well.

•   Consider and exclude other diagnoses.

Treatment 

Tactile stimulation, blood transfusion, continuous tube gastric feeds, caffeine or theophylline, nasal CPAP, or IPPV.

Prognosis 

Short-lived apnoeas appear to cause no harm and should resolve by 34wks gestation.